Thanks. Do you think the BDP 2 or 3 have enough power to access a 2 terabyte USB hard drive?
Yes, it will power any modern portable 2.5" drives from the likes of Seagate, Sandisk, or WD. As you go up in TB size, the power requirements do increase a little bit, but nothing that will cause issues. On my BDP-1 which had a far weaker power supply, I could simultaneously power 2 x 2.5" portable drives (2TB and 4TB) and also a flash drive.
The power limit of the USB ports was more of an issue back then because the BDP-1 had a weak power supply and the drives weren't as efficient and were bulkier as well. Nowadays, the drives have gotten more efficient and Bryston made sure to juice up the power supply with BDP-2 and BDP-3 to avoid the issues of BDP-1 and its smaller power supply.